Looking for a 300 block after my recent "big bang". My engine threw a rod.

ianmont

Member
Sadly my newly rebuilt 300 engine ran into some problems yesterday while driving my 64' Lesabre. The engine only had about 400 miles on the freshly rebuilt engine(built by me) when it decided to throw a rod and make a sizable hole in the block. :angry:
So, I'm looking for another usable 300 block. Does anyone have one they'd like to part with? I spent a lot of time and money on rebuiling this engine and am really quite down in the dumps.
Any help would be greatly appreciated.

Thanks, Ian
 
What Let Go?

Mistakes are always worth something. I plan on doing my '64 over soon. Is yours
11:1 compression? Auto trans? Did the cap come off? Piston still in bore? Valve fall in? Loose oil? Don't feal inferrior about doing your own work! Your miles ahead of check writers. We really want to know what went wrong.
 
Still not sure what exactly went wrong as the car is still in another city! Hopefully I'll get it this weekend and start tearing into it to see what went wrong. I'll fill everyone in once the tear-down starts.
 
Sorry about your engine. I have a complete drivetrain. 350 engine, 70,000 miles. located in Victoria Let me know if you are interested.

Eiunar
 
I agree......

You definitly need to find out why the engine tossed the rod.... there is a lot of questions here ,,,, this is not a normal happening,, I have built a ton of old engines and not ever had one to come apart with less than a 1000 miles.... I did have one that lost a cam at 3000 miles, due to not having zinc in the oil..... did you put zddp in the oil before you ever started the engine up???? if not , that could be the problem....
when you did the rebuild , were the rods reconditioned???? did a rod bolt break,,, did you use a torque wrench when you installed the rotating assembly?? Not trying to give you a hard time at all, pard ,, just trying to help, and keep the same thing from happening again.... i am big on guys doing the engines their selves.... I do,,, and it has saved me a bunch of money over the years.....If I can help , let me know.... I built and raced the 300 back in the 60's.... won more, broke less, and had more fun with that car than any other that I have owned...... BUT ANY FLAT TAPPET ENGINE MUST,MUST,MUST HAVE ZDDP ADDED TO THE OIL....or the engine will not live....
The 340 has a higher and wider deck, so the intake manifolds will not interchange,,, but I think the heads, and exhaust manifolds will.... but if you have headers expect them to rub the frame and you will have to work on them to make them work without rubbing.....been there , done that....
 
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I just posted a thread aluding to engine failure after a rebuild - - the timing main gear.
I hope to get some feedback so I don't go thru a "big bang"
 
Yes, I used a torque wrench on everything when putting the engine back together! And no, the rods weren't reconditioned by the machinist, and thats what failed, one of the rods basically came apart but I don't think the rod bolts broke. I'm not too sure what ZDDP is, so no, it wasn't added to the engine oil.
 
engine stuff....

Pal,, now days you must, must, must,,, put zddp in the oil,,, or lose the engine.... period... unless you are running a roller cam like all the late model cars use.... when all the manufactures went to roller cams, the oil companies dropped the zinc out of the oil they make and did not tell the public... if you run the oil you get now days without putting the zinc back in yourself you will lose the cam and the rest of the engine....i built a engine and did not put zinc in because I was ignorant about the change in the oil,,,, it lasted 3000 miles before the cam went south and the resulting metal chips in the oil destroyed the bearings..... that is how I know....:D:D
When you rebuild a engine, it is always good to xray the rods, cut the caps and recut the bores in the rod to round again... and on a race engine or real high mileage engine , install new rod cap bolts... I had a friend that owned a machine shop ,,,, in that shop he had a chevvy rod that looked perfectly normal,,, when he showed me the xray of that rod , it had a ball point pen inside it.... he constantly found flaws in rods by xraying them...
As for using the torque wrench, it is good that you did,,, when I was doing mechanic work , any time I had a reman engine block to install, I always torqed them before I installed the block,,, quite often, I found rods, mains, head bolts ect. not properly tightened.... recently had a man bring me a Buick engine that started knocking after 5 min. running time on start up.... i found no. 2 rod cap to be ''finger tight''....I check engine tork 3 times before bolting on the pan....
The small block buick engines have cast iron cranks that were tuftrided from buick and the rods are mallable iron not forged steel,,, so everything has to be up to snuff on those assemblies when you put them together or they will fail.... so limit rpm to factory reccomended levels.... not as tough as a nailhead....
 
Sadly my newly rebuilt 300 engine ran into some problems yesterday while driving my 64' Lesabre. The engine only had about 400 miles on the freshly rebuilt engine(built by me) when it decided to throw a rod and make a sizable hole in the block. :angry:
So, I'm looking for another usable 300 block. Does anyone have one they'd like to part with? I spent a lot of time and money on rebuiling this engine and am really quite down in the dumps.
Any help would be greatly appreciated.

Thanks, Ian

I would first start by determining the cause of the rod failure. If the rod shank ( beam ) didn't fracture and you found the rod bolt nuts in the pan, this means that the rod bolts were under torqued. If the rod bolt broke, very likely the bolts were over torqued. If the bearing spun ( seized on the crank journal ) and broke the shank, the most likely culprit is insufficient oil clearance or an out of round bearing saddle. If the crankshaft was reground and the rods were resized and you experienced a spun bearing, I would suggest you look for another machine shop on your next build.
At the present time, I don't have a 300 block.
 
i took my engine to get machined by a reputeable,30+ year established machine shop.
After, machine work done, I started to build engine.
Using plasti gauge, I found the crankshaft too loose in the front and insufficent clearance in the middle and rear. All new bearings.
I measured the crankshaft with two different digital calipers, and results shows crank was unevely machined. Reason, why my clearances are off.I'm returning to the machine shop to resolve machine shop's poor work quality. They did try to sell me work on the block, to fix there mistake. They wouldn't take responsibility. I will bring with me a witness and will discuss with them my loss from there workmanship.

I tested block and has no warpeage or other failure. So if I hadn't done this investigating, I may have been in your same situation.
Any one that is going to rebuild there engine , get a $15 digital caliper and measure your engine components, before they go to the machine shop.
 
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It saved me a bunch of money over the years .. If I can help, let me know ... I built the game back in the 1960s .... won 300 more, breaking the less, than any other I have more fun car.
 
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